Decision at Zulip about D3.js, Plotly

We use Plotly (just their open source stuff) for Zulip's user-facing and admin-facing statistics graphs because it's a reasonably well-designed JavaScript graphing library.

If you've tried using D3.js, it's a pretty poor developer experience, and that translates to spending a bunch of time getting the graphs one wants even for things that are conceptually pretty basic. Plotly isn't amazing (it's decent), but it's way better than than D3 unless you have very specialized needs.

Decision at datapile about D3.js

D3.js is an amazing library for doing visualizations, charts/graphs, etc. We are experimenting with it for metric visualizations, marketing graphs/charts, and basically anywhere we could use this amazing library. D3.js